The manufacture of cheese from milk concentrated by ultrafiltration (UF) is a radical innovation in cheesemaking which has been introduced to increase the yield of cheese. The increase in yield, which may exceed 20%, is due to incorporation into the cheese of soluble proteins, principally .alpha.-lactalbumin and .beta.-lactoglobulin. In conventional cheesemaking, these proteins are almost totally lost in the whey. Cheesemaking by UF offers other advantages, including reduced rennet consumption, a more uniform product, a less-polluting effluent, more efficient fat utilization, more uniform cheese weights, and the possibility of continuous cheese manufacture. In addition, the principal effluent (permeate) is particularly well suited to further processing, e.g. lactose crystallization or hydrolysis. The principle of manufacturing cheese from milk concentrated by UF (called retentate) in order to obtain increased cheese yield, is well known (Maubois et al, Aust. Pat. No. 477,339 (1978); Maubois et al, Le Lait, 51, 495, 1971) and is now used commercially in the manufacture of some varieties of soft (i.e. high moisture) cheese.
Ultrafiltration is a pressure-driven membrane separation process, utilizing pressures of 0.1-1.0 MPa and membranes with pore sizes of 5-35 nm. Macromolecules (e.g. proteins) and fat globules are retained on the feed side of the membrane, in the retentate, while the solvent (water) and small solute molecules (lactose, inorganic ions etc.) pass through the membrane and constitute the permeate. The principles of UF, the equipment available, and its application in dairy processing have recently been reviewed (Glover et al. (1978) J.Dairy Res., 45, 291). UF is now a commercially accepted technique for dairy processing. In most of the installed equipment, milk can be concentrated about 5-fold, but in new equipment now becoming available the attainable concentration factor may reach 9:1.
The well known process by which soft cheeses are manufactured from milk UF retentate was pioneered and patented by French workers (Maubois et al. op.cit). It is based on the concentration of whole or skim milk by UF, with the addition of high-fat cream in the latter case, to yield a product ("pre-cheese") containing about 60% moisture and having a gross composition similar to that of the desired cheese. Coagulation and fermentation of the pre-cheese affords the finished cheese directly, with little or no whey drainage or loss of whey proteins. The rennet requirement is reduced by approximately 80%. Camembert made by this process was initially claimed to be indistinguishable from the conventionally made cheese but more recently it has been reported to have flavour and textural defects.
The experimental manufacture of certain semi-hard cheeses from milk concentrated by UF has been reported. The varieties include Mozzarella, Gouda, blue-vein cheese, St. Paulin, Herve, and Havarti. In all cases, the desired moisture content was achieved by whey drainage. The volume of whey from the St. Paulin was exceptionally small, as this cheese was made from milk ultrafiltered to 45-46% solids by using new mineral membranes. These membranes are not in general use.
The manufacture of hard cheese from retentate presents difficulties much greater than those encountered in the manufacture of soft and semi-hard cheeses. The difficulties derive from the requirements of (i) removing more water from the retentate (typically 60% moisture in 5:1 retentate) in hard cheese manufacture than in soft cheese manufacture in order to achieve the desired composition, while (ii) retaining the sensory attributes of the cheese variety and (iii) simultaneously achieving a sufficient yield increase to justify introducing the UF-based process.